ON the AGROFORESTRY SYSTEM and in SITU CONSERVATION of MEDICINAL PLANT GERMPLASM in TRANS- NZOIA DISTRICT, KENYA J. M. Ochora 1
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ON THE AGROFORESTRY SYSTEM AND IN SITU CONSERVATION OF MEDICINAL PLANT GERMPLASM IN TRANS- NZOIA DISTRICT, KENYA J. M. Ochora 1, J. M. Onguso2 and J. I. Kany 3 1,3Department of Botany, Jomo Kenyatta University of Agriculture and Technology, Nairobi 2 Institute of Biotechnology Research, Jomo Kenyatta University of Agriculture and Technology, Nairobi E-mail: [email protected] Abstract In sub-Saharan Africa about 80% of the ever increasing population depends on ethnomedicine for their healthcare since modern medicine is mostly expensive or unavailable in rural homesteads. However, ethnomedicine is the one presently recognised as the most effective in treating new emerging diseases such as HIV/AIDS since no effective conventional medicine exists for their cure. Medicinal plants germplasm, which are the major sources of ethnomedicine form an important part of forests and riverine vegetation in Kenya. These important plants include Warburgia, Rhas spp., Aspilia, Acacia, prunus, Molinga, Brascae, Aloe, and Terminalia. These plants are not only useful to man as a source of medicine but are microhabitats for many animals as well as forming “refugia” to many insects species. In Kenya, due to land degradation and rampant deforestation in agriculturally high potential areas, medicinal plants genetic resource is threatened. The most medicinally popular of these plant species, which are mostly biome restricted, are facing extermination. This paper reports conservation concerns in agriculturally high potential Trans-Nzoia District in Kenya. The study based on field surveys revealed that of the ca. 806 plants species in 92 families about 36 species are used for medicinal purposes. The plants are threatened in their indigenous localities in the District. The study recommends participatory in situ plant conservation in the District along maize and wheat farm hedges. Key words: Agroforestry, in situ conservation, medicinal plants, indigenous medicines 120 1.0 Introduction As the demand for arable land and urban settlement increases in Kenya, more of the existing forest land is being excised for use as farmlands and urban infrastructural expansion. These activities have led to clearing of important forests and game reserves. The forest depletion seems to relate very well with population pressure backed by the fact that the backbone of Kenya’s economy is agriculture. Although surveys to map the proportion of plant species that are lost each year have not been comprehensively carried out, it is not surprising to discover that an overwhelming number of plants especially those of medicinal importance is eroded. As previously established, Kenya has a rich plant heritage with the most potent biochemicals (Kokwaro, 1983; Riley and Brokensha, 1988). Even if only a few medicinal plants have been documented for deforested areas of Kenya (Kanya 2004; Ochora et al., 2005) it is envisaged that many more destroyed plants fall under this category. Ex situ conservation strategies especially in garden environment (Frankel et al., 1995) are not suitable for trees and also for large populations of herbs, scrubs or shrub species. 2.0 Methods 2.1 Establishment of the Baseline and Number of Sampling (Transect Lines) The transect intercept method (Grieg-Smith, 1983)of sampling was employed. At each sampling site, a 1 km baseline with a west-east orientation was established. These points were randomly placed along this baseline through which a sampling line (transect) passed. Three transect lines (each 50 m) were established which intersected the baseline at midpoints (William, 1986). The orientation for each transect was randomized by selecting a number between 0o and 360o. 2.2 Measurement on Each Baseline As each line was traversed, the plants species intercepted by the transect line were identified to produce a species list (Agnew, 1994; Beetle, 1994). Where field identification of species was not possible in the field, voucher specimens were collected for later identification at the East African Herbarium (EA). The field work was done for a period of one year during cropping and non-cropping seasons. In each sampling site in the farms a baseline, 1 Km. long, was established orientating in a west-east direction. Three random points were located along the baseline through which sampling line (transect) passed. Transect lines were used such that as the line was traversed the plant species intercepted by the transect line were identified to produce a species checklist. The recorded plants were compared with the vegetation lists for Mt. Elgon forest available at the East African Herbarium. This montane vegetation is the remnant of indigenous plants of the District. 3.0 Results A checklist of plants ca. 806 in 92 families was established (Table 1). Except for plants in the categories of herbs and scrubs that easily rejuvenate from propagules in the farmlands, most shrubs and trees earlier recorded for Trans-Nzoia District are of rare occurrence. Conspicuously absent were the highly medicinal plants such as Warburgia, Prunus, Carissa, and Rhas (Table 2) that were once dominant in the region. 121 Table 1: A checklist of plant species recorded in Trans-Nzoia District during cropping and non-cropping seasons Family Plant Species Family Plant Species Acanthaceae Acanthus pubescens Amaranthaceae Achylanthes aspera Asystasia mysorensis Amaranthus caudatus Asystasia schimperi Amaranthus graecizana Barleria micrantha Amaranthus hybridus Dyschoriste radicans Celosia trigyna Hygrophila auriculata Cyathula polycephala Hypoestes forskahlii Justicia exigua Amaryllidaceae Scadoxus multiflorus Justicia flava Justicia striata Anacanthaceae Rhus natalensis Justicia whytei Rhus vulgaria Monechma debile Ruellia patula Anacardiaceae Lannea edulis Thunbergia elliotii Mangifera indica Thunbergia gregorii Ozoroa insignis Tithonia aethiopica Agave sisalan Annonaceae Annona squamosa Anthericaceae Chlorophytum gallabatense Apiceae Sanicula elata Apocynaceae Carissa edulis Araceae Arisaema enneaphyllum Landolphia buchananii Araliaceae Cussonia holstii Aslepiadiaceae Periploca linearifolia Striga hermonthica Asphodelaceae Bulbinella abyssinica Asteraceae Acanthospermum autriale Bignoniaceae Jacaranda mimosifolia Acanthospermum glabratum Markhamia lutea Acanthospermum hispidium Spathodea campanulata Acmella calirhiza Ageratina adenophora Boraginaceae Cordia Africana Ageratum conyzoides Cynoglosum coeruleum Ageratum houstoniamum Cynoglossum geometricum Anthemis tigreensis Cynoglosum lanceolatum Artemisia afra Ehretia cymosa Aspilia pluriseta Trifolium burchellianum Bidens pilosa Blumea aurita Brassicaceae Crambe kilimandscharica Balumea scaposa Raphanus sativus Bothriocline tomentosa Bromeliaceae Ananas comosus Centaurea mollis Cirsium buchwaldii Buddlejaceae Buddleja madagascariensis Conyza aegyptiaca Buddleja polystachya Conyza schimperi Conyza stricta Burseraceae Commiphora Africana Conyza sumatrensis Conyza volkensii Caesalpiniaceae Chamaecrista hildebranditii Crassocephalum afromontana Chamaecrista mimosoides Crassocephalum mannii 122 Piliostigma thonningii Crassocephalum montuosum Senna didymobotrya Crassocephalum picridifolium Senna singueana Crassocephalum vitellium Canjanus cajan Crepis carbonaria Dichrocephala integrifolia Capparaceae Cleome monophylla Emilia discrifolia Gynandropsis gynandra Euryops brownie Galinsoga alba Caricacea Carica papaya Galinsoga parviflora Gamolepis chrysanthemoifes Caryophyllaceae Cerastium indicum Gerbera viridifolia Cerastium octandrum Gnaphalium luteo-album Drymaria cordata Gnaphalium rubriflorum Silene burchellii Guizotia scabra Silene gallica Gutenbergia bonariensis Basella alba Gutenbergia cordofolia Helianthus annua Casuarinaceae Cassuarina cannighamii Helichrysum cymosum Helichrysum cymosum Calastraceae Maytenus heterophyla Helichrysum formosissimum Maytenus senegalensis Helichrysum gerberifolium Helichrysum odoratissimum Chenopodiaceae Chenopodium opulifolium Helchrysum setosa Chenopodium procerum Inula decipiens Lactuca capensis Compretaceae Compretum collinum Lagascea alata Compretum molle Lagascea mollis Laggera brevipes Commelinaceae Anailema johnsonii Launaea cornuta Commelina Africana Melanthera scandens Commelina benghalensis Microglossa pyrifolia Commelina repens Pycreus lanceolatus Schkuhria pinnata Convolvulaceae Convolvulus kilimandschari Sigesbeckia abyssinica Convolvulus mombasana Solanecio angulatus Dichondra repenes Sonchus asper Evolvulus alsinoides Sonchus oleraceus Falkia canescens Sporobolus Africana Ipomoea batatas Teclea nobilis Ipomoea kituiensis Tithonia diversifolia Ipomoea obscura Toddalia asiatica Ipomoea purpurea Vernonia auriculifera Vernonia brachytrichoides Crassulaceae Bryophylum pinnatum Vernonia galamensis Kalanchoe densiflora Vernonia hymenolepis Kalanchoe lanceolata Vernonia karaguensis Kalanchoe mitejea Vernonia lasiopus Vicia faba Cruciferae Brassica integrifolia Cupressaceae Cupressus lustanica 123 Brassica juncea Brassica nupus Cyperaceae Bothrichloa inscupta Brassica oleraceae Carex monostachya Erucastrum arabicum Cyperus alba Lepidium bonariense Cyperus assimilis Cyperus bulbosa Cucurbitaceae Coccinia grandis Cyperus dichrostachyus Cucumis aculeatus Cyperus distans Cucurbita pepo Cyperusgiolii Lagenaria abyssinica Cyperus hemisphaericus Lagenaria sphaerica Cyperus immensis Mormodica calantha Cyperus involucratus Mormodica foetida Cyperus kilimandschari Mormodica friesiorum Cyperus latifolius Mukia maderaspantana Cyperus macrocephala Peponium pepo Cyperus niveus Peponium volgellii Cyperus obusiflorust Zornia